Flow method based on cloud point extraction for fluorometric determination of epinephrine in human urine

A novel stepwise injection fluorometric method for the determination of epinephrine in human urine has been developed. In the current study, the stepwise injection analysis (SWIA) was successfully combined with on-line in-syringe cloud point extraction (CPE) and fluorometric detection. The procedure was based on the epinephrine derivatization in the presence of o-phenylenediamine followed by the preconcentration stage based on the CPE with the nonionic surfactant Triton X-114. After the phase separation into a syringe of the flow system, the micellar phase containing the epinephrine derivative was transported to a fluorometric detector. The excitation and emission wavelengths were set at 447 nm and 550 nm, respectively. The conditions of epinephrine derivatization and CPE have been studied. The calibration plot constructed using the developed procedure was linear in the range of 1·10⁻¹¹–5·10⁻⁷ mol L⁻¹. The limit of detection, calculated as 3 σ of a blank test (n = 10), was found to be 3·10⁻¹² mol L⁻¹. The proposed method was successfully applied for the determination of epinephrine in human urine samples.     

直接荧光光度法测定水中痕量酚

建立了一种新的荧光光度法分析水中痕量酚.水中的酚经紫外光照射后,激发强荧光λ_(ex)=273nm,λ_(em)=302nm),能直接进行荧光光度测定.检出限0.03μg·L~(-1),相对标准偏差0.29%,回收率97.5%～102.5%.方法简单、快速、精密度和准确度高、无毒、安全.     

光谱法研究11-羟基喜树碱与牛血清白蛋白的相互作用

在生理pH条件下用荧光光谱法和紫外光谱法结合化学计量学来研究10-羟基喜树碱(10-HCPT)与牛血清白蛋白(BSA)的相互作用,结果发现,10-HCPT对BSA的内源荧光有静态猝灭作用。以华法林作为标记药物,采用三维荧光技术,分别对竞争实验过程进行扫描,进而用平行因子法(PARAFAC)处理所得三维数据,并根据蛋白质结合位上药物的置换作用确定了10-HCPT的结合位置是BSA的site I。利用同步荧光光谱,考察了10-HCPT对BSA构象的影响,10-HCPT的加入使BSA构象发生变化,BSA内部残基所处环境的疏水性下降。     

Supramolecular interaction of cucurbit[n]urils and coptisine by spectrofluorimetry and its analytical application

The supramolecular interaction of a homologous series of cucurbit[n]uril (CB[n], n = 5, 6, 7, 8) hosts and coptisine (COP) was studied by spectrofluorimetry. All of the CB[n]s were found to react with COP to form 1:1 host-guest stable complexes and the fluorescence intensity of the complexes was greatly enhanced. The apparent association constants of the complexes were 1.44 × 10⁴, 1.28 × 10⁴, 1.86 × 10⁴ and 1.26 × 10⁴ L mol⁻¹ for CB[5], CB[6], CB[7] and CB[8], respectively. In addition, CB[5] and CB[7] exhibited a higher fluorescence signal than CB[6] and CB[8]. The fluorescence intensity of the complex with CB[7] was enhanced 70-fold compared to that of the studied drug itself. Based on the significant enhancement of fluorescence intensity of supramolecular complex, a simple, rapid, highly sensitive, and selective spectrofluorimetric method was developed for the determination of COP in aqueous solution in the presence of CB[7]. At the optimum reaction conditions, a linear relationship was obtained in the range from 0.05 to 1700 ng mL⁻¹ with a detection limit of 0.012 ng mL⁻¹. The proposed method was successfully applied for the determination of the drug in urine and serum samples.     

抑制荧光动力学法测定痕量对硝基苯胺

在硫酸介质中,痕量对硝基苯胺对溴酸钾氧化罗丹明B荧光猝灭具有抑制作用,由此建立了抑制动力学荧光法测定痕量对硝基苯胺的分析新方法。考察了酸度、反应温度、反应时间、各种试剂等条件对抑制反应的影响。在最佳实验条件下,此方法线性范围为0.68×10-7—5.44×10-7g/mL,检出限为4.76×10-8g/mL。该方法应用于环境水样的测定,回收率为96%—107%。     

Spectrofluorimetric Determination of Famotidine in Pharmaceutical Preparations and Biological Fluids. Application to Stability Studies

A simple, economic, selective, and stability indicating spectrofluorimetric method was developed for the determination of famotidine (FMT); is based on its reaction with 9, 10-phenanthraquinone in alkaline medium to give a highly fluorescent derivative measured at 560 nm after excitation at 283 nm. The fluorescence intensity - concentration plot was rectilinear over the concentration range of 50–600 ng/ml with minimum quantification limit (LOQ) of 13.0 ng/ml and minimum detection limit (LOD) of 4.3 ng/ml. The factors affecting the development of the fluorescence intensity of the reaction product were carefully studied and optimized. The method was applied for the determination of FMT in its dosage forms. The stability of the compound was studied, and the proposed method was found to be stability indicating one. The results obtained were in good agreement with those obtained by the official method. Furthermore, the method was applied for the determination of FMT in spiked and real human plasma. The mean % recovery (n = 4) was found to be 99.94 ± 0.24, and 105.13 ± 0.64 for spiked and real human plasma, respectively. The composition of the reaction product as well as its stability constant was also investigated. Moreover, the method was utilized to investigate the kinetics of both alkaline and oxidative induced degradation of the drug. The apparent first order rate constant and half life time of the degradation product was calculated. A proposal of the reaction pathway was postulated.     

Sensitive Determination of Norfloxacin by the Fluorescence Probe of Terbium (III)- Sodium Dodecylbenzene Sulfonate and Its Luminescence Mechanism

The fluorescence system of the norfloxacin-Tb³⁺- sodium dodecylbenzene sulfonate (SDBS) was investigated in this paper. The experiments indicated that the fluorescence intensity of the Tb³⁺-SDBS was greatly enhanced by the norfloxacin. On the basis of the above findings, a sensitive fluorimetric method for determining the norfloxacin was established. The fluorescence intensity was measured by a 1-cm quartz cell with the excitation wavelength of 290 nm and the emission wavelength of 545 nm. The enhanced fluorescence intensity of the system (Δ F) showed a good linear relationship with the concentration of norfloxacin in the range of 5.0×10⁻⁹ mol L⁻¹–2.0×10⁻⁶ mol L⁻¹, its correlation coefficient was 0.9991 and the detection limit (S/N=3) was 1.2×10⁻⁹ mol L⁻¹. The presented method was used to determine the norfloxacin in real pharmaceutical samples. The luminescence mechanism was also discussed in detail. In the fluorescence system of the norfloxacin-Tb³⁺-SDBS, the SDBS not only acted as the surfactant, but also acted as the energy donor.     

Spectrofluorimetric Determination of Opium Alkaloids by Mixed Anhydride Reagent

Abstract

The spectrofluorimetric determination of five major opium alkaloids by malonic acid-acetic anhydride reagent is reported. The fluorescence characteristics of various alkaloidal systems and the effect of different parameters like temperature, time of heating and diluent on the fluorescence intensity are described. The interference of various foreign substances has also been checked.     

三氟乙酰丙酮—Gd（Ⅲ）—CTMAB配合物体系荧光法研究及应用

本文研究了Ｇｄ－三氟乙酰丙酮－ＣＴＭＡＢ的三元配合物荧光体系，并用钇的测定，最低检测限为：０．００３μｇ／ｍＬ，Ｇｄ在０．００５－０．４μｇ／ｍＬ范围内呈线性关系，回归方程Ｆ＝３１．６５ｃ＋０．２１，相关系数为ｒ＝０．９９９６，将此法用于稀土矿的痕量Ｇｄ的测定，与ＩＣＰ－ＡＥＳ法相比，结果令人满意。     

Simple, rapid, and highly sensitive detection of diphosgene and triphosgene by spectrophotometric methods

Methods for the detection and estimation of diphosgene and triphosgene are described. These compounds are widely used phosgene precursors which produce an intensely colored purple pentamethine oxonol dye when reacted with 1,3-dimethylbarbituric acid (DBA) and pyridine (or a pyridine derivative). Two quantitative methods are described, based on either UV absorbance or fluorescence of the oxonol dye. Detection limits are ∼4 μmol/L by UV and <0.4 μmol/L by fluorescence. The third method is a test strip for the simple and rapid detection and semi-quantitative estimation of diphosgene and triphosgene, using a filter paper embedded with dimethylbarbituric acid and poly(4-vinylpyridine). Addition of a test solution to the paper causes a color change from white to light blue at low concentrations and to pink at higher concentrations of triphosgene. The test strip is useful for quick on-site detection of triphosgene and diphosgene in reaction mixtures. The test is easy to perform and provides clear signal readouts indicative of the presence of phosgene precursors. The utility of this method was demonstrated by the qualitative determination of residual triphosgene during the production of poly(bisphenol-A carbonate).